This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cytomegalovirus (CMV) is an important opportunistic pathogen in AIDS. Although CMV disease manifests in the setting of immunosuppression, the mechanisms underlying impaired CMV-specific T cell immunity in AIDS are not well understood. To determine whether loss of CD4-positive T cells can impair functionality of CMV-specific CD8-positive T cells, we are investigating CMV reactivation in rhesus macaques following in vivo antibody-mediated CD4+ and CD8+ T lymphocyte depletion.